1. Field of the Invention
The present invention relates to a system for converting a natural language question into a query to search a certain database or a certain knowledgebase and performing search by use of the query and a method thereof, and more particularly, to a system for converting a natural language question into a query to search a standardized knowledgebase by using a deep language analysis technology and searching for a correct answer by using the converted query, and a method thereof.
2. Discussion of Related Art
There have been inventions or studies on a method for converting a natural language question into a query to search a certain database or knowledgebase, which has been conducted by using a method of matching a natural language question to a predefined search query.
However, the method has limitation in the form of the natural language question and the range of extracted knowledge/correct answer. In addition, a method of generating a query language for a certain type of knowledgebase has difficulty in using various types of knowledgebase.
In a relevant patent “Natural Language Question-Answering Search System for Integrated Access to Database, FAQ and Web Site”, a natural language question is assigned a semantic code that contains Schema information of Korean language wordnet information/domain dictionary DB, a query language assigned with a sematic code includes a vocabulary, a part of speech, PLO information, syntax information and a semantic code of a query sentence, and the form of Structured Query Langue (SQL) that is a dialog type database query sentence previously stored through a lexio-syntactic pattern determiner described in regular expressions is determined. The determined SQL query is used to find the optimum answer in database.
Another relevant patent, “Natural Language Question Answering System And Method Based On Deep Semantics (U.S. Ser. No. 13/171,391)” suggests a method of finding a correct answer by receiving a natural language question, performing deep analysis on the natural language question, mapping the natural language question into a “deductive database” query, and searching in “deductive database” by using the mapped query. However, the knowledgebase to be searched is limited to deductive database.
The above described relevant patents use a method of selecting a query that is mapped to an input question among predefined standardized queries. In this case, a query specialized in knowledgebase is created at a level of surface lexicon analysis on a natural language question, so there is limitation of the format and the content of a question at the time of mapping a natural language question and elements of knowledgebase.